Incremental resistance module



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INVENTOR F24 L 1144 90 BY g t 7 M ATTORNEYS United States Patent 3,334,323 INCREMENTAL RESISTANCE MODULE Frank L. Ward, Exeter, N.H., assignor to Clarostat Mfg. Co., Inc., Dover, N.H., a corporation of New York Filed Sept. 9, 1965, Ser. No. 486,124 7 Claims. (Cl. 338-77) This invention relates generally to variable resistors, and more particular, to a module containing a plurality of resistance elements which can be incrementally selected to give a precise desired resistance between two terminals.

There are many situations, especially during Work in a laboratory, where it is necessary to vary the resistance between two points either for experimental purposes or in the trimming of a unit. In order to do this, the person doing the work can interchange resistances by selection of specific resistance elements, or as is usually the case, the person can use a potentiometer. The difliculties of using a number of resistances and interchanging them are obvious. With a potentiometer the user upon achieving the desired result can not know what the resistance is unless he is working with a calibrated potentiometer or unless he has instruments available for measuring the resistance between the two points.

It is a principal object of this invention to provide a unit with which a user can vary the resistance between two points incrementally and in known amounts.

It is another object of this invention to provide such a unit in modular form which can be readily combined with other units of the same type to develop the desired resistance range.

It is another object of this invention to provide a variable resistor in which the resistance can be varied in known steps so that when the desired result is achieved a single resistor of known ohmic value can the substituted for the experimental unit.

It is another object of this invention to provide a variable resistance module which can be used under certain circumstances as an integral part of a final product.

It is a further object of this invention to provide such a resistance which can be used on a breadboard in a laboratory and in the use of which the resistance can be varied with a minimum of effort.

An incremental resistance module constructed in accordance with the teachings of this invention and the method of using the same is described herein with reference to the drawings in which:

FIG. 1 is an exploded perspective view of an incremental resistance module constructed in accordance with the teachings of this invention;

FIG. 2 is a partially sectional longitudinal view from the front of the incremental resistance module shown in FIG. 1;

FIG. 3 is a partially sectional longitudinal view taken along the line 3-3 in the direction of the arrows, as

shown in FIG. 2;

FIG. 4 is a partially sectional transverse view taken along the line 44 in the direction of the arrows, as shown in FIG. 2;

FIG. 5 is a partially sectional view taken along the line 5-5 in the direction of the arrows, as shown in FIG. 3; and

FIG. 6 is a view from above of several incremental resistance modules constructed in accordance with the teachings of this invention in ganged relation.

In the figures the housing of the unit is indicated by the numeral 10 consisting of side walls 11 and 12 and front and rear walls 13 and 14, respectively. End wall 15 of the-housing provides one end of the assembled unit and the second end is provided by removable terminal block 16 which closes the open end 17 of the housing.

- ends 17 and 15 and A raised rectangular portion 18 of front wall 13 projects outwardly from the front wall terminating short of also projects beyond wall 11 to provide a flanged portion 18a which is dimensioned identically with flanged portion 19 which projects from rear wall 14. Flanges 18a and 19 are provided with facing longitudinal slots 20 and 21 respectively which provide with side Wall 11 of the unit a track for receipt of a T-like projection such as projection 22 which projects from side wall 12 of the module. Projection 22 is formed with outwardly directed ears 23 and 24 which are constructed to be received within facing slots identical with slots 20 and 21 previously described so that like modules can be gained in a manner that will be more fully described below.

Terminal block 16 includes a main body portion 25 which is rectangular in configuration and designed to be received snugly within the opening provided in end 17 of the housing. The uppermost end of the terminal block is formed with a grip portion 26 which is greater in transverse dimension than the transverse dimension of the housing so that the grip portion can be utilized in joining and separating the terminal block and the housing. Also the grip portion in overlying the terminal edge 17a of end 17 of the housing encloses the unit and prevents undesiraable bodies from entering the internal portion of the housing. Rectangular cutouts 27 and 28 are provided in the housing to receive respectively rectangular projections 29 and 30 of the terminal block to position the terminal block in a positive manner relative to the housing. Additionally, transverse cylindrical slots 31 are provided in the interior surface of front and rear walls 13 and 14 of the housing to receive transverse cylindrical projections 32 of the terminal block in order to lock the terminal block in closed position.

The terminal block and the housing are formed of any suitable material which can be molded or machined. Such material can be plastic, Bakelite, or can even be wood if it is desired. It is preferred that a non-electrical conductor be used and that the material be plastic or Bakelite. The end 15 of the housing and the terminal block are provided with semi-circular through channels 33 and 34 respectively to enable the user to fasten the module to a breadboard in the well known manner.

The interior surface of side walls 11 and 12 of the housing are provided with channels 35 and 36 for receipt of the edges of insulating plate 37, End wall 15 and terminal block 16 are also provided with channels 38a and 38b respectively for the same purpose. These channels can be formed in any suitable manner either by cutting out portions of the respective walls or by providing raised portions on the walls. Additionally shoulders 39 and 40 are provided on the interior surfaces of side walls 11 and 12 respectively for abutment with portion 25 of terminal block 16.

The front wall 13 including the raised portion 18 thereof is provided with a plurality of circular through holes indicated by the letters A through I with which the square through holes formed in insulating plate 37 register in the assembled condition of the unit. The holes insulating plate 37 are also indicated by the letters A through J.

Electrically conducting plates 41 and 42 are supported by the insulating plate 37 by receipt of lugs 43 and 44 in slots 45 and 46, respectively, and the embracing of edges 37a and 37b of the insulating plate by lugs 47 and 48. Shorting plates 41 and 42 are thus mounted by the insulating plate separate from and insulated from each other. A suitable electrical connection is made between lug 47 and terminal 49 and lug 48 and terminal 50 through holes 51 and 52 in the terminal block.

A plurality of identical conducting plates are indicated by the numerals 53 through 56 and supported by the insulating plate by means of lugs on the conducting plates passing through slots in the insulating plate. Thus lugs 57 and 58 of plate 53 are received within slots 59 and 60 of the insulating plate, lugs 61 and 62 of insulating plate 54 are received within slots 63 and 64 of the insulating plate, lugs 65 and 66 of plate 55 are received within slots 67 and 68, and lugs 69 and 70 of plate 56 are received within slots 71 and 72. Additional lug 73 of plate 42 is received within slot 74. Also it is noted that each of the electrical conducting plates is provided with turned over portions to be received within respective rectangular slots A through J. Thus the insulating plate supports the various conducting plates and certain of the lugs as appear in the drawings are turned over to provide a firm grip of the conducting plate on the insulating plate. Any suitable means of supporting the conducting plates on the insulating plate can be utilized and the method disclosed herein does not necessarily have to be followed in order to keep within the scope of the invention.

It is noted that each of the conducting plates is separated or isolated from the remaining conducting plates. A plurality of resistors indicated by the numerals 75 through 79 are mounted in the unit and as seen best in FIG. 5, resistor 75 is terminated at one end at lug 73 and its remaining end is terminated at lug 67. Resistor 76 is terminated at lugs 67 and 63, resistor 77 is terminated at lugs 63 and 61, resistor 78 is terminated at lugs 61 and 57, and resistor 79 is terminated at lugs 57 and 43. Hence the resistors are connected in series with one end of the series combination terminated at lug 73, which is part of conducting plate 42, and the remaining end of the series combination is terminated at lug 43, which is part of electrical conductor 41.

With this arrangement if resistors 75 through 78 are each of a value of 100 ohms and resistance 79 is 500 ohms the total resistance available between terminals 50 and 49 is 900 ohms. Shorting plug 80 consisting of insulated knob 81 and electrical conducting plug portion 82 is provided with the knob 81 formed so that it can be grabbed by the fingers of the user and conducting portion 82 formed to be received within the lettered holes in the housing and the insulating plate. Thus insertion of plug 80 in lettered hole A results in providing electrical continuity between conducting plates 41 and 42 shorting out all of the resistance and providing zero resistance or a short, between terminals 49 and 50. Insertion of the plug in lettered hole I however merely places the plug in contact with shorting plate 42 and does not short out any of the resistors, allowing a full 900 ohms to appear between terminals 49 and 50. Placing of the plug 80 in any of the lettered holes, intermediate holes A and J results in the shorting out of a number of the resistors providing a load increment of resistance between terminals 49 and 50. For example, in FIG. 2 the plug is shown in lettered hole C and resistors 77, 78 and 79 are shorted out so that only resistors 75 and 76 are in the circuit providing 200 ohms between terminals 49 and 50.

As described heretofore, the module is provided so that it can be gauged with identical modules to provide additional resistance combinations. Thus, in FIG. 7 the module thus described is shown and indicated by the numeral 83 ganged with modules 84 and 85. It is noted that normally the openings A through J would be numbered zero through nine and when ganged the arrangement would be in decade steps so that module 83 would provide a resistance value of the value shown times 84 would provide a resistance value of the value shown times 10 and, 85 would provide a value times 1. The mechanical attachment of modules 83 and 84 has been accomplished in FIG. 7 with the mechanical attachment of module 85 in the process of being accomplished. Conducting lead 86 is shown connecting terminal 50 electrically with the terminal 87 of module 84 so that a total resistance, which is a combination of the modules 83 and 84, appears across terminals 49 and 88 and since the plug 80 is shown in lettered hole C. Module 83 is contributing 200 ohms to the combination and since the plug 89 is shown in lettered 4 hole D in module 84 the module 84 is contributing 30 ohms to the combination, so that the resistance appearing between terminals 49 and 88 is 230 ohms. A total of 999 ohms is available however in one ohm increments.

The ganging of modules mechanically is accomplished since each of the modules is provided on one side with a track-like configuration, such as that previously described with respect to the description of module 83 wherein facing channels 21 and 20 are provided. Each of the modules is also provided with a T-like structure, such as that previously described with respect to module 83 so that ears 23 and 24 can be received within the facing channels 20 and 21 of like units. The dimension of the ears 23 and 24 is such that they will be snugly received within the channels 20 and 21, respectively, and the spacing of ears 23 and 24 from the wall 12 of the housing is such that the outside edges of flanges 18a and 19 can be received snugly within the channel provided by the spacing between each of the ears and the side wall 12. Thus the outer edge portion 89 of flange 18a can be received in a channel 90 formed by car 23 and side Wall 12 and the outer edge portion 91 of flange 19 can be received in a channel 92 formed by car 24 and side wall 12.

Thus, among others, the several objects in the invention as specifically aforenoted, are achieved. Obviously, numerous changes in construction and re-arrangement of parts might be resorted to without departing from the spirit of the invention as defined by the claims.

I claim:

1. An impedance unit for use in electric circuitry including in combination, a nonconducting casing, first and second conducting plates supported by and within said casing in spaced relationship with each other, first and second impedance terminating portions of said first and second conducting plates respectively, first, second and intermediate impedance means supported by said casing, first and second conducting means, said first impedance means being terminated at one end at said first impedance terminating portion and at its remaining end at said first conducting means, said second impedance means being terminated at one end at said second impedance terminating portion and at its remaining end at said second conducting means, said intermediate impedance means being terminated at said first and second conducting means, said first and second conducting means being electrically spaced from said conducting plates and each other, said first and second conducting means being spaced from said conducting plates at fixed predetermined distances, means for electrically connecting a selected one of said conducting means and a selected one of said conducting plates consisting of an electrically conducting plug insertable in the space between said selected conducting means and said selected conducting plate and slots formed in said casing allowing passage of said plug therethrough.

2. An impedance unit in accordance with claim 1 in which the facing edges of said selected conducting means and said selected conducting plate are formed to receive said plug and maintain it in position in a press fit.

3. An impedance unit for use in electric circuitry including in combination a casing formed of a nonconducting material, first and second spaced conducting plates supported by and within said casing, a conducting portion of said first conducting plate projecting toward said second conducting plate and forming a first plug receiving slot respectively with said second conducting plate, first and second conducting means between said conducting plates and spaced therefrom and from each other, said first conducting means forming second and third plug receiving slots with said first and second conducting plates respectively, said second conducting means forming fourth and fifth plug receiving slots with said first and second conducting plates, first, second and intermediate impedance members, said first impedance member terminated at said conducting portion and said first conducting means, said second impedance member terminated at said second conducting means and said second conducting plate, said intermediate impedance member terminated at said first and second conducting means, unit terminating means terminating said conducting plates, an electrically conducting plug receivable in a selected one of said slots for shorting and slots formed in said casing allowing passage of said plug therethrough.

4. An impedance unit for use in electric circuitry including in combination a non-conducting casing, first and second spaced conducting plates supported by and within said casing, a conducting portion of said first conducting plate projecting toward said second conducting plate and forming first and second plug receiving slots respectively with said first and second conducting plates, first, second, third and fourth conducting means between said conducting plates and spaced therefrom and from each other, said first conducting means forming third and fourth plug receiving slots with said first and second conducting plates respectively, said second conducting means forming fifth and sixth plug receiving slots With said first and second conducting plates respectively, said third conducting means forming seventh and eighth plug receiving slots with said first and second conducting means respectively, said fourth conducting means forming ninth and tenth plug receiving slots with said first and second conducting plates respectively, a first impedance member terminated at said conducting portion and said first conducting means, a second impedance member terminated at said first and second conducting means, a third impedance member terminated at said second and third conducting means, a fourth impedance member terminated at said third and fourth conducting means, a fifth impedance member terminated at said fourth conducting means and said second conducting plate, unit terminating means terminating said conducting plates and an electrically conducting plug receivable in a selected one of said slots.

5. An impedance unit in accordance with claim 4 in Which each of the impedance members is a resistive element.

6. An impedance unit in accordance with claim 5 in which a face cover of said casing is provided with openings registering with said slots formed by said conducting plates and said conducting means whereby said plug can pass through said casing to be received Within a selected slot.

7. An impedance unit in accordance with claim 6 in Which said casing is elongated with parallel first and second flat sides, facing projecting portions are provided on the edges of said first side to form a channel and a complementary projection is formed on said second side and receivable in a channel of the type formed on said first side whereby like units may be mechanically attached.

References Cited UNITED STATES PATENTS 1,189,931 7/1916 Frohne 338-77 1,781,802 11/1930 Bandoly 338-77 2,373,156 4/1945 Wilhelm 338-77 2,944,237 7/1960 Solow 338-77 2,988,722 6/1961 Zabel 338-77 RICHARD M. WOOD, Primary Examiner.

W. D. BROOKS, Assistant Examiner. 

1. AN IMPEDANCE UNIT FOR USE IN ELECTRIC CIRCUITRY INCLUDING IN COMBINATION, A NONCONDUCTING CASING, FIRST AND SECOND CONDUCTING PLATES SUPPORTED BY AND WITHIN SAID CASING IN SPACED RELATIONSHIP WITH EACH OTHER, FIRST AND SECOND IMPEDANCE TERMINATING PORTIONS OF SAID FIRST AND SECOND CONDUCTING PLATES RESPECTIVELY, FIRST, SECOND AND INTERMEDIATE IMPEDANCE MEANS SUPPORTED BY SAID CASING, FIRST AND SECOND CONDUCTING MEANS, SAID FIRST IMPEDANCE MEANS BEING TERMINATED AT ONE END AT SAID FIRST IMPEDANCE TERMINATING PORTION AND AT ITS REMAINING END AT SAID FIRST CONDUCTING MEANS, SAID SECOND IMPEDANCE MEANS BEING TERMINATED AT ONE END AT SAID SECOND IMPEDANCE TERMINATING PORTION AND AT ITS REMAINING END AT SAID SECOND CONDUCTING MEANS, SAID INTERMEDIATE IMPEDANCE MEANS BEING TERMINATED AT SAID FIRST AND SECOND CONDUCTING MEANS, SAID FIRST AND SECOND CONDUCTING MEANS BEING ELECTRICALLY SPACED FROM SAID CONDUCTING PLATES AND EACH OTHER, SAID FIRST AND SECOND CONDUCTING MEANS BEING SPACED FROM SAID CONDUCTING PLATES AT FIXED PREDETERMINED DISTANCES, MEANS FOR ELECTRICALLY CONNECTING A SELECTED ONE OF SAID CONDUCTING MEANS AND A SELECTED ONE OF SAID CONDUCTING PLATES CONSISTING OF AN ELECTRICALLY CONDUCTING PLUG INSERTABLE IN THE SPACE BETWEEN SAID SELECTED CONDUCTING MEANS AND SAID SELECTED CONDUCTING PLATE AND SLOTS FORMED IN SAID CASING ALLOWING PASSAGE OF SAID PLUG THERETHROUGH. 